De website van William Powells: http://www.esf.edu/EFB/powell/. Williams TED-lezing: ‘Reviving the American forest with the American chestnut’ (april 2013), http://tedxtalks.ted.com/video/Reviving-the- American-forest-wi.

Artikel over de quagga. ‘The Quagga and Science: What Does the Future Hold for This Extinct Zebra?’ (2013), Heywood, Perspectives in Biology and Medicine, volume 56, http://muse.jhu.edu/article/509324.

Er zijn verschillende reportages over de wisenten die in de Karpaten zijn uitgezet. The Guardian schreef over de eerste keer: ‘Return of the European bison’ (mei 2014), The Guardian, http://www.theguardian. com/environment/2014/may/21/-sp-european-bison-europe-romania- carpathian-mountains.

Een bioloog die erg positief staat tegenover de experimenten: ‘As far as we can go, as far as we want to go …’ Greene, Centre for humans and nature, http://www.humansandnature.org/conservation-extinction- harry-w.-greene.